The invention concerns a coating device for the coating of a web material, such as paper or cardboard webs, that are supported, preferably, by a backing roll. The coating device includes a doctor fashioned as a doctor blade band which is retained in a doctor holder supported by a doctor beam.
Coating devices for web material are known in the prior art. In prior art devices a blade may be used, which smoothes the coating substance that is applied on the web. Either a round doctor bar or also a doctor blade may the used as a doctor. Both elements have their specific applications, although the blade involves the grave disadvantage of heavy, partly disuniform wear.
It has frequently been found that the coating application in the case of a blade displays disuniformities that do not occur with a roll type doctor. Attempts have been made, with the aid of profile correction devices that permit a local variation of the contact pressure applied on the blade, to accomplish a uniformity of the coating. This has not, however, always been completely successful. Accordingly, the problem underlying the present invention is to provide a device where a uniform coating application is also achieved during the entire operation.